Fix type checking in test files

[mmv08]

This PR:

• Fixes the type checking in test files by including the test directory in the list of typescript's watched directories
• As a side effect, it included the test directory in the final build. It was fixed by using a separate config for the production build that extends the main one but excludes the test directory from the production build. The solution was taken from here
• I had to fix types in one place where the Contract interface was used from a different package (ethers/contracts) instead of ethers directly. I also ran npx yarn-deduplicate to remove duplicated packages.

[github-actions]

Pull Request Test Coverage Report for Build 5080528329

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 97.071%

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Totals
Change from base Build 4991446336:	0.0%
Covered Lines:	308
Relevant Lines:	316

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